struct S {
    int a;
    int b;
};
struct S arr[2] = {[1] = {3, 4}, [0] = {1, 2}};

int main() {
    if (arr[0].a != 1)
        return 1;
    if (arr[0].b != 2)
        return 2;
    if (arr[1].a != 3)
        return 3;
    if (arr[1].b != 4)
        return 4;
    return 0;
}
